Why would the primates of Africa be less affected by die offs than others of this time? Could it be because they are isolated from 'wolf wars' going on in Eurasia? Note that unlike humans, the other primates do not develop chins during this time. Or maybe their lack of domesticated wolves means they don't suffer some of the new sicknesses wolf owners do (illnesses passing across species). Or maybe it has nothing to do with the domestication of wolves, and everything to do with location and other matters. The humans of Africa may not be competing as directly and robustly with other primates there as their cousins are in Eurasia. Closer competition often means closer interaction: ergo, new diseases passed between different primate lines. Or, it could be that the non-African primates (including humans) tend to cluster near the coastlines of southern and southeast Asia, as well as elsewhere. If so, unexpected tsunamis from local or distant earthquakes, eruptions, and meteor impacts could periodically wipe out entire local populations along those coasts-- while those living in the African interior would largely be protected from such events.

Note that this harsh period may be what spurs humanity into its massive tool-aided opportunistic exploitation and long term storage of wild grains-- a precursor to fixed-site agriculture.